Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
  • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
  • G01T1/02—Dosimeters
  • G01T1/06—Glass dosimeters using colour change; including plastic dosimeters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
  • C09K11/06—Luminescent materials, e.g. electroluminescent or chemiluminescent containing organic luminescent materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Definitions

• This invention relates to radiation sensitive devices, such as coatings, films, plaques and blocks, for imaging and monitoring dose of high-energy radiations such as ultraviolet (UN) radiation, electrons, X-rays, protons, alpha particles and neutrons utilizing radiation sensitive material such as diacetylenes.
• the radiation sensitive devices can be used for monitoring dose in three dimensions.
• the invention also relates to other radiation sensitive materials, such as leuco and pH sensitive dyes with acid producing compounds.
• materials and processes for molding and casting radiation sensitive devices are also provided.
• High energy radiation including those having energy higher than 4 eN, such as UN light, X-rays, gamma rays, electrons, protons, alpha particles, neutrons, and laser radiation are used for a variety of applications, such as curing of coatings and cross- linking of polymers, recording images and information, radiography, nondestructive testing and diagnostic and radiation therapy. Their exposure needs to be monitored.
• any material such as a diacetylene, a radiochromic dye, a mixture of leuco and/or pH sensitive dyes with an acid producing compound and alike, or mixture thereof, which undergoes at least one noticeable or monitorable change, such as a change in color, fluorescence, opacity and magnetic resonance, is referred to herein as "radiation sensitive compound", “radiation sensitive material” or “radiation sensitive formulation”.
• radiation sensitive compound a material
• radiation sensitive formulation a material
• silver halide film composed mainly of fine particles of silver bromide/iodide in gelatin is widely used as the film for recording images and information, diagnostic and industrial radiography and monitoring radiation therapy and dose.
• silver halide film has many disadvantages and drawbacks: (a) making an emulsion of silver halide is a multi-step and expensive process, (b) the film requires protection from ambient light until fixed, (b) the developing and fixing processes are "wet" and chemical based, and require about five minutes developing time, and the concentrations of individual solutions and chemicals, time and temperature of developing and fixing must be strictly controlled and (c) the image is two-dimensional. Hence, it is desired to have a highly sensitive, self-developing, dry fixing film, which is not affected by white light.
• the thickness of coating is usually limited to less than about 30 microns.
• the sensitivity of the diacetylene film is about fifty times lower than that of silver halide film for certain applications. If the coating of the diacetylene film is fifty times thicker, fifty times lower dose can be monitored. However, it is not practical to make such a thick coating from a solution or emulsion because it is not possible to dry such a thick coating using the conventional drying ovens and processes. Hence, there is a need for a technique for making thick coatings of such radiation sensitive materials. [0006] Thick plaques and blocks of a variety of plastics are routinely casted from their monomers or oligomers such as polyacrylics.
• Thick coatings, films, fiber, plaques or blocks are also prepared by reacting a monomer or oligomer with another reactant.
• an epoxy polymer can be prepared by reacting an epoxide, preferably an oligomeric epoxide with a primary amine or a diepoxide with a di-secondary amine
• a polyurethane/polyurea can be prepared by reacting a diisocyanate, preferably an oligomeric, with a diol or diamine, preferably an oligomeric diol or diamine.
• pre-polymers These non-diacetylenic monomers and oligomers are referred to hereafter as pre-polymers. It is possible to make a mixture of these pre-polymers and diacetylenes followed by the polymerization of the pre- polymers.
• a film, plaque or block containing diacetylene can be easily prepared by crystallization of a diacetylene in a pre-polymer followed by polymerization of the pre- polymer or vice versa. For a given concentration of the diacetylene, a one hundred times thicker film or plaque will able to monitor a one hundred times lower dose.
• a shaped- articles containing a radiation sensitive material such as diacetylene can be prepared by (1) crystallization of diacetylene in one of the liquid pre-polymers, (2) mixing it with an appropriate amount of the other pre-polymer and (3) casting or molding the mixture in the desired form.
• any regular or irregularly shaped-article can be produced by molding, i.e., injecting a molten polymer in to a mold.
• Radiation sensitive shaped- article, such as fiber, film, plaque, rod, and block can be prepared by melt mixing or dissolving radiation sensitive materials such as diacetylenes in a molten polymer followed by molding into the shaped-article.
• Coatings, films, fiber, rods, plaques or blocks, with or without radiation sensitive material such as a diacetylene are individually or collectively, referred hereafter to as "shaped-articles", “radiation sensitive shaped-articles”, “radiation sensitive devices” or simply “devices”.
• the process of molding or casting the coatings, films, fibers, plaques or blocks from pre-polymers or polymers is referred hereafter to as molding-process, molding-technique, casting-process, casting-technique or in general shaping-teclmique or shaping-process.
• the resultant shaped-articles will develop color upon irradiation due to the polymerization of the diacetylene.
• the shaped-articles will be able to monitor a greatly lower dose of X-ray because of the greater thickness.
• the molding-technique can provide radiation sensitive shaped-articles of unlimited thickness, size and shape, e.g., from a thin coating/film to thick plaque/block/shaped-articles.
• Molding-technique includes processes of mixing/dissolving a diacetylene in a pre-polymer or a molten polymer.
• a formulation containing a mixture of, dissolved or dispersed, a radiation sensitive material and a pre- polymer or polymer, or like formulation from which one can prepare shaped-articles is referred herein to as "molding mixture", "molding formulation” or "shaping formulation”.
• Conformal radiotherapy aims to maximize tumor dose while minimizing the dose to the surrounding healthy tissue through the use of complex radiation therapy treatment planning and dose delivery systems.
• new treatment planning techniques are being developed including CT-based virtual treatment simulation, and 3D (three dimensional) planning for conformal treatments with applications to both external beam and brackytherapy treatment modalities.
• Brackytherapy is the placement of small radiation sources within or near the tumor. Radioactive sources such as Ytterbium- 169 and Iodine- 125 seeds are used for brackytherapy.
• Gel Dosimetry is a technique in which radiation sensitive gels are used to record and measure the distribution of absorbed radiation dose in tissue-like materials. These measurements are used to verify dose calculations and dose delivery techniques in radiation therapy.
• ferric ions produce a stronger paramagnetic enhancement of the water-proton NMR relaxation rate, their distribution may be determined by MRI.
• Maryanski et al US Patent #5,633,584, introduced a system based on radiation induced polymerization and crosslinking of acrylic monomers, which are uniformly dispersed in an aqueous gel.
• the formation of crosslinked polymers in the irradiated regions of the gel increases the NMR relaxation rates of neighboring water protons. Polymerized regions can be seen visually, as the crosslinked polymer is insoluble in water and precipitates from the aqueous phase of the transparent gel, which therefore becomes increasingly opalescent (and ultimately white) as the radiation dose increases.
• this system has many drawbacks, such as (1) sensitivity to visible blue and UV lights, (2) high sensitivity to temperature of irradiation, (3) short shelf life, e.g., a few weeks at room temperature, (4) very high sensitivity to oxygen, (5) short archival life, e.g., readings should be taken within a week, (6) toxic vinyl monomers require special handling and disposal, (7) not being self-supporting requires a glass container, (8) image is opaque and not in colors, and (9) during the measurement the light is scattered and hence one has to map with NMR technique. Hence, there is a need for a 3D dosimetry system, which does not have the above drawbacks.
• thermoset polymers as binders and diacetylenes as indicators.
• An optical scanner may incorporate a laser, photodiode detectors, and a rotating platform for the shaped-article or alternatively a lamp, color filter, light diffuser, rotating platform for the block and a digital camera and/or similar optical scanning system. Data can be acquired for each incremental rotation of the platform. Using the set of optical-density projections obtained, a cross-sectional image of the radiation field is then reconstructed. Doses can be determined from calibration data of optical density and dose and optical density measurement. Optical scanners are described in U.S. Pat. Nos. 5,321,357 and 6,218,673 and by Mark Oldham, J.H. Siewerdsen, Anil Shetty, and D.A., Jaffery, Med. Phys., vol.
• a plastic block prepared by the shaping technique containing diacetylene or other radiation sensitive material would eliminate most of the drawbacks of the gel dosimetry.
• the block will be essentially muscle tissue equivalent in both elemental composition and density.
• the radiation sensitive material in the block will develop color in proportion to radiation dose, thereby creating a permanent three-dimensional image of dose distributions in the block.
• Quantitative 3D dosimetry data can be calculated from the scans of the block using MRI or optical scanning.
• Tomographic analysis of an irradiated polymer block can yield important dosimetry data for the new and highly complex treatment modalities which are being introduced into radiation oncology such as stereotactic radiosurgery, conformal radiation therapy, the dynamic wedge, scanning electron beams and energy-modulated proton beams.
• the radiation sensitive shaped-articles such as plaque and/or block can be used for monitoring and imaging, e.g., (1) personnel and area dosimeters, (2) radiographic films (3) determining dose in three dimensions, and (4) imaging radiation sources.
• diacetylenes R- C ⁇ C-C ⁇ C-R, where R is a substituent group.
• Diacetylenes polymerize in the solid state either upon thermal annealing or exposure to high-energy radiation [Adv. Polym. Sci., vol. 63, 1 (1984)].
• the solid monomers are colorless or white, the partially polymerized diacetylenes are blue or red, while the polydiacetylenes are metallic being usually a copper or gold color.
• Polydiacetylenes are highly colored because the "pi" electrons of the conjugated backbone are delocalized. The color intensity of the partially polymerized diacetylenes is proportional to the polymer conversion.
• Diacetylenes are not sensitive to visible radiation (long wavelength).
• Luckey and Boer in U.S. Patent No. 3,772,027 disclose a diacetylenic photosensitive element containing inorganic salts, such as titanium dioxide, zinc oxide, cadmium iodide, and cadmium sulfide as sensitizers to make the element sensitive to visible radiation.
• Another similar patent U.S. Patent No. 3,772,028) issued to Fico and Manthey discloses a photosensitive element sensitized to visible radiation by the addition of pyrylium salts including thiapyrylium and selenapyrylium salts. Amplification of poorly imaged crystalline diacetylenic compositions is obtained in U.S. Patent No.
• Patel in U.S. Patent No. 4,235,108; 4,189,399; 4,238,352; 4,384,980 has disclosed a process of increasing the rate of polymerization by cocrystallization of diacetylenes.
• Patel and others in U.S. Patent Nos. 4,228,126; and 4,276,190 have described an inactive form of diacetylenes for storing and method of rendering them active prior to use by solvent, vapor and/or melt recrystallization.
• Mong-Jon Jun at el U.S. Patent No.
• 3,836,368 describe 2,4-hexadiyn-l,6- bis(n-hexyl urethane), referred to here in as "166", which turns red upon short wavelength UV irradiation. They prepared a coating formulation by adding water to a solution of 166 in polyvinylpyrrolidone in methanol. U.S. Patent No. 5,420,000 described a highly sensitive coating of 166. Although 166 is sensitive to UV radiation, the reactivity is not sufficient to use it for applications, such as diagnostic X-ray film.
• the phosphor of the fluorescence screen absorbs X-rays and emits near UV or visible light. Intensifying screens made with calcium tungstate phosphors have been in use since the time of Roentgen. Around 1972, a new phosphor, gadolinium oxysulfide was developed which emits in the green region and film sensitized to absorb green light was developed. About the same time other phosphors, such as barium fiuorochloride and lanthanum oxybromide, which emit in the blue region, were developed.
• phosphors have been reported in the literature including terbium activated rare earth oxysulfide (X 2 O 2 S where X is gadolinium, lanthanum, or yttrium) phosphors (T.F. Soules and MN. Hoffman, Encyclopedia of Chemical Technology, Vol.14, pp 527-545, 1981 and references quoted therein).
• Gadolinium and tungsten have very high atomic numbers and also have a high-energy absorption coefficient. The following combinations have been used for this purpose: GdOS:Tb(III), LaOS:Tb(III), LaOBr:Tb(III), LaOBr:Tm(III), and Ba(FCl) 2 :Eu(II).
• Convertors/phosphors are usually used as a screen in the form of a fine powder dispersed in a polymeric binder.
• the screens are placed in contact with the emulsion of silver halide film during X-ray irradiation.
• the prior art does not describe a convertor/phosphor, which is in the form of a transparent coating being a solid solution or complex of a converter with a polymeric binder.
• the use of these converters in the under coat, radiation sensitive coat and topcoat of the device is also not described.
• the phosphors emitting short wavelength UV light can be used as a screen to amplify the radiation image.
• a diacetylene is dissolved and/or crystallized, at least from one of the reactants (e.g., an oligomeric diol) and then mixed with the other reactant (e.g., an oligomeric diisocyanate) or in the mixture of the reactants.
• a catalyst is added to the mixture for their polymerization.
• the shaping-mixture can then be coated on a substrate or casted into a film, plaque or block.
• di and polyisocyanates including poly(hexamethylene diisocyanate), poly(propylene glycol) tolylene 2,4-diisocyanate terminated, poly(l,6 hexamethylene diisocyanate) trimeric, poly[(phenyl isocyanate)-e ⁇ -formaldehyde] and several commercially available diisocyanates, e.g., hexamethylene diisocyanate, Lord Chemical UR-312 Resin, Lord Chemical UR-324 Resin and Tadco isocyanate Formula 11B51 A.
• di and polyisocyanates including poly(hexamethylene diisocyanate), poly(propylene glycol) tolylene 2,4-diisocyanate terminated, poly(l,6 hexamethylene diisocyanate) trimeric, poly[(phenyl isocyanate)-e ⁇ -formaldehyde] and several commercially available diisocyanates, e.g., hexamethylene diiso
• the radiation sensitive shaped-articles were also obtained by dissolving radiation sensitive materials, e.g., diacetylenes in monomeric and oligomeric pre- polymers such as acrylics followed by polymerization of the pre-polymers with a catalyst, such as benzoyl peroxide.
• a promotor e.g., N ⁇ -Dimethyl-p- toluidine
• Diacetylenes were crystallized either by cooling the mixture prior to polymerization of the pre- polymers or by cooling the polymerized system at a lower temperature.
• a solvent for diacetylene was used to adjust the temperature required for crystallization of the diacetylene.
• Desired size of the diacetylene crystals and radiation sensitivity was obtained by controlling a variety of parameters such as nature and concentration of diacetylene, nature of pre-polymer, nature and concentration of solvent for diacetylene and pre-polymer, nature and concentration of plasticizer, nature and concentration of promoters and catalysts for polymerization of pre-polymers and other additives such as UV absorbers and antioxidants.
• radiation sensitive materials such as diacetylenes can be added in a molten polymer and the mixture can then be molded into a thin film, plaque and/or block. Upon cooling the mixture, diacetylenes crystallize into fine crystals, which polymerize into colored polymers upon irradiation with ionizing radiation.
• the conventional method of making shaped objects can be used to make radiation sensitive shaped objects.
• the shaping-mixture of a diacetylene can also be coated with a variety of coating techniques, e.g., gravure, fiexo, air knife, brush, calendar, cast coating, curtain, dip, extrusion, blade, floating knife, kiss roll, off-set, reverse roll, rod, spray, squeeze roll and wire wound rod on a substrate e.g., a polyester film.
• the coating can become solid in seconds to minutes.
• the substrate can be coated on both the sides with the shaping mixture.
• a self-supporting film can be prepared by pouring/coating the shaping mixture on a substrate e.g., plastic film/belt, having a release coat of silicone or Teflon R .
• the self-supporting, radiation sensitive film can also be made from the shaping mixture by the conventional methods such as melt extrusion, of making film. This film can be used as a diagnostic, portal and verification film. A piece of the film can be used as a dosimeter.
• the thickness of the X-ray films is usually about 200 microns.
• Shaped radiation sensitive articles can be obtained by pouring the mixture containing pre-polymer, diacetylene and other additives into a properly shaped mold and letting the pre-polymer polymerize.
• self-developing shaped-articles such as film, plaque and blocks prepared by shaping-techniques for monitoring dose, recording and imaging with radiation, such as UV light, electrons, X-rays, neutrons, or gamma rays
• radiation such as UV light, electrons, X-rays, neutrons, or gamma rays
• at least one radiation sensitive material such as diacetylenes, a binder such as polyurethane, polyacrylics, and polystyrene, optionally having a solvent, an activator, converter material, capable upon radiation with high energy electrons, X- rays, gamma rays, neutrons, of generating secondary radiation which is capable of inducing polymerization of the diacetylene to form a colored image.
• R-C ⁇ C-C ⁇ C-R a specific diacetylene
• 166 undergoes a red-to-blue color change when the partially polymerized 166 is heated near or above its melting point.
• a preliminary toxicity study indicates that 166 is nontoxic.
• Diacetylenes such as 155, 156 and 16PA can cocrystallize with 166 to increase the radiation reactivity.
• the 85:15 mixture of 166:156 is a preferred diacetylene mixture for the system.
• a variety of other diacetylenes, both liquid and solid, such as tricosa-10,12- diynoic acid (TC), pentacosa-10,12-diynoic acid (PC), methylester of TC and PC and 4BCMU [5,7-dodecadiyn-l,12-bis(n-butoxycarbonyl methylurethane), R-C ⁇ C-C ⁇ C-R, where R (CH 2 ) 4 OCONHCH 2 COO(CH 2 ) 4 H] can also be used.
• the other diacetylenes that can be used are described in U.S. Patent Nos. 4,215,208; 5,149,617 and 5,095,134.
• a self-developing shaped-articles such as film, plaque and block prepared by a shaping-technique for developing an image from exposure to X-ray, gamma ray, electron, or neutron radiation
• a radiation sensitive material such as a diacetylene, capable of undergoing a color change when contacted with ultraviolet light, X-rays, alpha particles, or electrons, thereby forming an image
• a binder such as polyurethane, polyacrylics, and polystyrene, optionally having a solvent, an activator, converter material, capable upon radiation with high energy electrons, X-rays, gamma rays, neutrons, of generating secondary radiation which is capable of inducing polymerization of the diacetylene to form a colored image.
• self-developing shaped-articles such as film, plaque and block prepared by a shaping-technique for developing an image from exposure to narrow or coherent beam such as laser of ultraviolet and other high energy radiations comprising of at least one radiation sensitive material such as diacetylene capable of undergoing a color change when contacted with said radiation, thereby forming an image, wherein said image is capable of being fixed by heating.
• narrow or coherent beam such as laser of ultraviolet and other high energy radiations
• at least one radiation sensitive material such as diacetylene capable of undergoing a color change when contacted with said radiation, thereby forming an image, wherein said image is capable of being fixed by heating.
• a means of controlling the size of the crystals of diacetylenes by controlling the effects of many parameters, including (1) the nature and concentrations of diacetylenes, plasticizers, additives, pre-binders, and nucleating agents, (2) temperature of dissolution of diacetylenes, (3) rate of quenching the mixture/solution, (4) nature and concentration of solvent, (5) temperature at which the solution/mixture are cooled, and (6) temperature of crystal growth.
• a method of making the fine dispersion of radiation sensitive materials which involves making a solution of diacetylenes in at least one pre-polymer, quenching the mixture at a lower temperature to freeze the mixture and then thawing the solid at a higher temperature for growing crystals of the diacetylenes.
• UV absorbers such as maleic acid, sodium salicylate, 2-ethylhexyl salicylate, octyl methoxycinnamate, benzophenone, benzophenone tetracarboxylate or finely grinded pigments into the binder or into a top coat.
• the UV absorbers are not added into the topcoat when screens emitting UV lights are used to amplify the image or used for imaging with UV laser or UV light.
• a method of irradiation of radiation sensitive shaped- articles such as plaque and block with high energy radiation such as X-ray, protons, neutrons and electrons producing an image of the source and the beam, scanning the image with a scanner and determining dose distribution in three dimensions.
• radiation sensitive shaped-article such as film, plaque and block by mixing radiation sensitive materials and polymerizable monomers and oligomers followed by polymerization of the monomers and oligomers.
• methods of making radiation sensitive shaped-articles such as film, plaque and block by mixing radiation sensitive materials with molten polymers followed by cooling.
• a radiation sensitive molded or casted shaped polymeric device including coating, film, fiber, rod, plaque and block for monitoring radiation dose of UV, X-ray, gamma ray, electron, protons, alpha particles or neutron radiation prepared by polymerization of at least one mono and difunctional monomer or oligomer containing at least one radiation sensitive material capable of developing or undergoing a color, fluorescence, or opacity change, with or without activator, when contacted with UV, X-ray, gamma ray, electron, protons, alpha particles or neutron, and optionally additives such as UN absorber, convertor, surfactant and solvent.
• a process of making radiation sensitive molded or casted shaped polymeric devices including coating, film, fiber, rod, plaque and block for monitoring radiation dose of UN, X-ray, gamma ray, electron, protons, alpha particles or neutron radiation prepared by solidification of molten polymer containing at least one radiation sensitive material capable of developing or undergoing a color, fluorescence, or opacity change, with or without activator, when contacted with UN, X-ray, gamma ray, electron, protons, alpha particles or neutron, and optionally additives such as UN absorber, convertor, surfactant and solvent.
• a method for monitoring high energy radiation comprising the step of placing the radiation sensitive shaped-article in the path of UV, X-ray, gamma ray, electrons, protons, alpha particles or neutron radiation and monitoring the radiation dose by monitoring the change caused by the radiation and monitoring the dose by monitoring the change.
• a process of monitoring dose in three dimensions comprising steps of irradiation of radiation sensitive device and scanning the device.
• a method of imaging and measuring a three- dimensional dose distribution of a radiation source in the radiation sensitive device comprising the steps of irradiating the device such that the optical properties are changed upon radiation, optically scanning the object at various angles, detecting and measuring light projection data indicative of optical changes in the device, calibrating the optical change in the device to the dose of the energy; and mapping the dose of the energy in the device.
• Figure 1 A schematic cross-section of one embodiment of the film device of the invention where a substrate is coated on one side with the radiation sensitive layer.
• Figure 2. A schematic cross-section of another embodiment of the film device where a substrate is coated on both sides with the radiation sensitive layer.
• Figure 3. A schematic cross-section of the self-supporting film.
• Figure 4. A schematic cross-section of the plaque dosimeter.
• Figure 5. A schematic cross-section of the block dosimeter.
• Figure 6. A side view representation of a block dosimeter exposed to 10 Gy of 100 KVP X-ray.
• Figure 7. A top view representation of a block dosimeter exposed to 10 Gy of 100 KVP X-ray.
• Figure 8 A representation of an image taken across a scanned image of summation of 16 single transverse adjacent slices through the center of the cylindrical sample identical to that shown in Figure 7.
• Figure 9. The density profile and isodose plot across the transverse image of Figure 8.
• Figure 10 A schematic representation of a scanning device for reading an image in an inventive device.
• the radiation sensitive shaped-article in its simplest form is comprised of a substrate 10 having at least one radiation sensitive layer 20 comprised of at least one radiation sensitive composition 21, a polymeric binder 22, optionally a solvent 23, a convertor 24 for converting high energy incident radiation to low energy radiation, a plasticizer 25 and other additives 26 such as an activator.
• the substrate 10 may have a substratum layer, i.e. undercoat for increasing adhesion between the substrate 10 and the radiation sensitive layer 20.
• the radiation sensitive layer, 20 may have a topcoat 30 which may contain additives, such as a convertor 24 and a UV absorber 31.
• the device can also have a protective layer.
• the device can have more than one radiation sensitive layer and can be made from different radiation sensitive formulations to provide different properties such as colors.
• the lowest detection limit of the dose can be reduced to half as illustrated in Figure 2 by having the radiation sensitive layer 20 and topcoat 30 on both the sides of the substrate 10.
• the radiation sensitive layer on each side may be the same or made from different radiation sensitive formulations to produce different colors and there could also be more than one layer on each side.
• the device can be a self supporting film comprised of at least one radiation layer 200, comprised of at least one radiation sensitive composition 21, a polymeric binder 22, and optionally a solvent 23, a convertor 24, a plasticizer 25 and other additives 26 such as activator.
• the radiation sensitive self- supporting layer 200 may have a topcoat 30 which may contain additives, such as a convertor 24 and a UV absorber 31.
• the plaque can also have a protective layer.
• a much lower dose can be monitor by casting or molding the device in form a thick, e.g., 0.1 to 10 mm thick plaque, as shown in Figure 4.
• the plaque may be comprised of at least one radiation sensitive thick layer 2000, comprised of at least one radiation composition 21, a polymeric binder 22, and optionally a solvent 23, a convertor 24, a plasticizer 25 and other additives 26.
• the radiation sensitive layer 2000 may have a topcoat 30 which may contain additives, such as a convertor 24 and a UV absorber 31.
• the plague can also have a protective layer.
• a large block can be molded or casted as shown in Figure 5.
• the block may be comprised of at least one radiation composition thick block 20000, comprised of at least one radiation sensitive composition 21 and polymeric binder 22, and optionally a solvent 23, a convertor 24, a plasticizer, 25 and other additives 26.
• the block could be cubic rectangular or any other shape of a body part.
• Figure 6 is a representation of a side view of a vial containing a block prepared as per example 18. The sample was irradiated with 10 Gy of 100 KeV X-ray beam which was collimated using metal washers having a hole of 0.7 cm.
• Figure 7 is a representation of a top view of the block of Fig. 6 prepared as per example 18. A beam passing through the block can be seen representing exposure. The color intensity decreases from top to bottom.
• Figure 8 illustrates an across scanned image of summation of 16 single transverse adjacent slices through the center of the cylindrical sample identical to that shown in Figure 7. An optical scanner described in example 23 was used to scan the block.
• Figure 9 illustrates the density profile and isodose plot across the transverse image of Figure 8.
• Figure 10 is a schematic representation of a scanner for use in the present invention.
• the scanner generally represented at 99, scans the device, 100.
• a radiation source, 102 generates a radiation beam, 103, which impinges the item, 100.
• the beam intensity is decreased resulting in an attenuated beam, 104.
• a detector, 105 detects the intensity of the attenuated beam, 104.
• the source is preferably on a frame, 106, thereby allowing the sample, or radiation source, to be translated and rotated thereby allowing multiple samples to be read.
• the preferred diacetylenes are the derivatives of 2,4-hexadiyne, 2,4- hexadiyn-l,6-diol, 3,5-octadiyn-l,8-diol, 4,6-decadiyn-l,10-diol, 5,7-dodecadiyn-l,12- diol and diacetylenic fatty acids, such as tricosa- 10,12-diynoic acid (TC), pentacosa- 10,12-diynoic acid (PC), their esters and cocrystallized mixtures thereof.
• the most preferred derivatives of the diacetylenes, e.g. 2,4-hexadiyn-l,6-diol are the urethane and ester derivatives. The following are some of the preferred derivatives of 2,4- hexadiyn-l,6-diol:
• Cocrystallized mixtures including: Containing 80 weight percent or above of 166 85:15 mixture of 166 and 156 90:10 mixture of 166 and 156 and 4:1 mixture (TP41) of tricosadiynoic acid and pentacosadiynoic acid.
• the urethane derivatives can be prepared by reacting diacetylene-diol, e.g., 2,4-hexadiyn-l,6-diol with appropriate isocyanates (e.g. n-hexylisocyanate) in a solvent, such as tetrahydrofuran, using catalysts, such as di-t-butyltin bis(2-ethylhexanoate) and triethylamine as indicated below: Catalysts
• Ester derivatives can be prepared by reacting e.g., 2,4-hexadiyn-l,6-diol with appropriate acid chlorides in a solvent, such as dichloromethane, using a base, such as pyridine as the catalyst; i.e., Pyridine
• Asymmetrical diacetylenes can be prepared by the Cadiot-Chodkiewicz type reaction methods.
• Diacetylene 166, and closely related diacetylenes are preferable due to high radiation sensitivity, low thermal reactivity, crystallization to an inactive phase from the melt which allows for heat fixability, a readily distinguishable red to blue color change when partially polymerized and heated to near or above the melting point and low toxicity.
• Cocrystallization can be achieved by dissolving two or more diacetylenes, preferably conjugated, prior to molding.
• the resulting cocrystallized diacetylene mixture such as TP41 (4:1 mixture of TC:PC) has a lower melting point and significantly higher radiation reactivity.
• the reactivity can also be varied by partial neutralization of diacetylenes having -COOH and -NH2 functionalities by adding a base such as an amine, NaOH, Ca(OH)2, Mg(OH)2 or an acid such as a carboxylic acid, respectively.
• a base such as an amine, NaOH, Ca(OH)2, Mg(OH)2 or an acid such as a carboxylic acid, respectively.
• 166 can be co-crystallized with other diacetylenes, e.g. 155, 157, 154 and 156, which are described above. Though certain diacetylenes, such as 155, increase the reactivity of 166, the partially polymerized cocrystallized diacetylenes provide a red color upon melting.
• 156 increases the radiation reactivity of 166 and provides a blue color upon melting the partially polymerized diacetylene mixture.
• 166 can be cocrystallized with different amounts of 156. Preferred is where the amount is 5 - 40 weight percent of 156 to 166, most preferred are 90:10 and 85:15 respective weight ratios of 166:156. As used herein "9010” and “8515” refer to these specific cocrystallized mixtures.
• Other asymmetrical derivatives, including different functionalities, e.g., ester as one substituent and urethane as the other, can also be prepared. A procedure for synthesis of a 90:10 mixture of 166 and 16PA is given in U.S. Patent No. 5,420,000.
• the preferred diacetylenes are those which have a low (below about 150°C) melting point and crystallize rapidly when cooled at a lower temperature, e.g. room temperature.
• diacetylenic compounds are those having an incorporated metal atom and they can be used as in-built convertors.
• Diacetylenes having functionalities such as amines, ethers, urethanes and the like can form complexes with inorganic compounds. It is possible to synthesize diacetylenes having an internal convertor, which is covalently bonded, such as boron and mercury, lithium, copper, cadmium, and other metal ions.
• the -COOH functionality of TC, PC and TP41 can be neutralized with lithium ion and synthesis of R-C ⁇ C-C ⁇ C-Hg- C ⁇ C-C ⁇ C-R is reported (M. Steinbach and G.
• the metal atom, such as mercury atom thereby incorporated into the diacetylene can emit short wavelength irradiation upon irradiation with photons and electrons.
• the following terminologies are used for defining the reactivity (polymerizability) of a diacetylene.
• the polymerizable form of a diacetylene(s) is referred to as "active". If a diacetylene is polymerizable with radiation having energy higher than 4 eV, wavelength shorter than 300 nm, then it is referred to as "radiation active”. If it is polymerizable upon thermal annealing then it is referred to as "thermally active".
• the preferred form of diacetylene is one, which is highly to moderately radiation active with little or no thennal reactivity.
• Thermal reactivity can be decreased and radiation reactivity can be increased by cocrystallization and molecular complexation.
• the shaped-articles can be stored at lower temperature to slow down the thermal reactivity.
• diacetylenes are the most preferred radiation sensitive materials
• other radiation sensitive materials can also be used for making the devices using the procedure and formulations described here.
• the radiation sensitive materials/formulations described in Imaging Systems, K.I. Jacobson and P.E. Jacobson, John Wiley and Sons, NY 1976 can also be used to make radiation sensitive shaped- articles.
• silver halides e.g., AgCl, AgBr, Agl, silver molybdate, silver titanate, silver mercaptide, silver benzoate, silver oxalate, and mixtures thereof; salts and organic, inorganic and organometallic complexes of metals such as iron, copper, nickel, chromium and transition metals, e.g., mercury oxalate, iron oxalate, iron chloride, potassium dichromate, copper chloride, copper acetate, thallium halides, lead iodide, lithium niobate, and mixtures thereof; aromatic diazo compounds, polycondensates of diazonium salts, the naphthoquinone diazides, photopolymers and photoconductive materials, are also preferred radiation sensitive compositions for making the devices.
• metals such as iron, copper, nickel, chromium and transition metals, e.g., mercury oxalate, iron oxalate, iron chloride,
• radiochromic dyes such as new fuschin cyanide, hexahydroxy ethyl violet cyanide and pararose aniline cyanide, leuco crystal violet, leuco malachite green and carbinol dyes such as malachite green base and p-roseaniline base and those described in U.S. Patent Nos. 2,877,169; 3,079,955; and 4,377,751.
• radiochromic dyes and other dyes which change color with change in pH can be used in combination with materials which produce acid upon irradiation, e.g., organic halocompounds, such as trichloroethane, ethyltrichloroacetate, chlorinated paraffins and chlorinated polymers.
• Chlorinated polymers and oligomers which can be used for monitoring radiation with pH sensitive dyes include polymers and copolymers of vinyl chloride, vinylidene chloride, epichlorohydrin and similar halogenated monomers.
• polyvinyl chloride polyvinylidene chloride, polyepicholorohydrin and their copolymers.
• a film, plaque and block of halogenated polymers such as polyvinyl chloride, polyvinylidene chloride, polyepichlorohydrin and their copolymers such as polyvinyl chloride, polyvinylidene chloride, polyepichlorohydrin and their copolymers containing a pH sensitive dye, with and without activators and additives such as heat stabilizers, can be used for monitoring radiation.
• the acid produced can react with the pH sensitive dye and change color.
• iodinium salts such as, diphenyliodinium hexafluoroarsenate, and diphenyliodinium chloride produce protonic acids, such as, HC1, HF, HBF4 and HASF6 upon irradiation with high energy radiation ( J. Crivello,
• Exemplary dyes include: acid alizarin violet ⁇ , acid black 24, acid black 48, acid blue 113, acid blue 120, acid blue 129, acid blue 161, acid blue 25, acid blue 29, acid blue 40, acid blue 41, acid blue 45, acid blue 80, acid blue 93, acid fuschin, acid green 25, acid green 27, acid green 41, acid orange 74, acid red 1, acid red 114, acid red 151, acid red 88, acid violet 17, acid violet 7, acid yellow 99, acridine orange, acridine orange base, acridine orange G, acridine yellow G, acriflavine hydrochloride, alcian blue 8GX, alcian yellow, alizarin, alizarin blue black S ⁇ , alizarin complexone, alizarin complexone dihydrate, alizarin red, alizarin violet 3R, alizarin yellow GG, alizarin yellow R, alkali blue 6B, alkali fast green 10GA, alphazurine A, aluminon, amino
• Transparent radiation sensitive shaped-articles are the most preferred. If the shaped-article is opaque, semi transparent or translucent, it is desirable that it becomes substantially transparent after processing, i.e., heating. A radiation sensitive shaped- article, which is opaque, can also be used for certain applications such as radiation dosimetry. Transparency for 3D dosimetry is required only if optical scanning is used. For other techniques, such as MRI, it is not necessary to have transparency or uniform thickness. Several techniques, such as grinding the radiation sensitive compositions into very fine particles and crystallizing into very fine particles by techniques such as rapid quenching can be used to provide the required transparency. A transparent radiation sensitive shaped-article will provide a clear image with high resolution for an optical scanning and monitoring system.
• diacetylenes For monitoring a color change in reflectance mode, transparency is not required.
• diacetylenes polymerize only in the solid (crystalline) state, they must be in the crystalline state in the binder at least at the time of irradiation.
• the binder for the diacetylene should be highly transparent.
• the preferred crystal size of the diacetylene is smaller than 300 nm, preferably less than 100 nm (1 micron).
• the refractive indices of the radiation sensitive material and that of the binder should also be as close as possible.
• the refractive index of organic materials is usually low and within a narrow range.
• Amorphous polymers are desirable but semi-crystalline polymers can be used as binders if they provide a significantly transparent coating.
• a crystalline polymer can be made amorphous by cross-linking. Binders which wet the surface of the radiation sensitive materials such as diacetylene crystals will also provide higher transparency.
• a wetting agent or surfactant can increase the wetting of the crystals by the binder.
• a binder, which is transparent and has a refractive index close to that of diacetylene and/or preferably wets the diacetylene crystal surface is desirable.
• a shaped-article is considered transparent if over about 25% of the incident light is transmitted through the shaped-article.
• a shaped-article is considered opaque if more than about 75% of the light is absorbed, reflected or scattered rather than being transmitted through.
• a colored shaped-article can also be transparent at one wavelength of incident radiation if that light is not absorbed or partially absorbed. However, the same colored shaped-article can appear opaque to a different wavelength of incident radiation, if its color absorbs the incident radiation.
• Transparency in the shaped-articles such as coating, film, plaque and block can be achieved by making solid solution of radiation sensitive material and the binder. In order to polymerize diacetylenes, they must crystallize into particles finer than the wavelength of the light used for scanning. As an alternative, the same goal can be achieved by either using diacetylenes which are solid at the temperature of irradiation and liquid either at room temperature or temperature of scanning. Such goal can also be achieved either by using liquid diacetylenes or solution of diacetylenes. Transparency can also be achieved by grinding crystalline diacetylenes into fine particles below the wavelength of light, dispersing in a proper pre-polymer followed by its polymerization.
• the term "convertor(s) n is used for any material, substance or mixture, which can be complexed or doped with other substances, which when irradiated with high energy radiations, both ionizing and nonionizing, produces relatively lower energy radiation, either of the same or different type, via any process including scattering, attenuation, fluorescence, phosphorescence, and conversion.
• Inorganic and organometallic compounds are preferred as converters because they have the ability to transfer/convert high-energy radiation into lower energy radiation via many processes, such as scattering, absorbance, fluorescence, and phosphorescence.
• the selection of a convertor depends upon the type of radiation to be monitored and its energy. For example, lead and barium salts are good convertors for monitoring X-ray radiation and boron, lithium salts are good convertors for measuring thermal neutrons.
• lead and barium salts are good convertors for monitoring X-ray radiation and boron
• lithium salts are good convertors for measuring thermal neutrons.
• Elements having high atomic number (Z), such as lead, are also preferred.
• Other convertors include alloys, salts, and free metals of zinc, tin, silver, tungsten, molybdenum, platinum, gold, copper, iodine, and bromine.
• the resulting image can be amplified by incorporating convertor materials into the radiation sensitive mixture, under coat, topcoat, and preferably into all these.
• the convertors will absorb high energy X-ray, radiation, electrons, and neutrons and convert the absorbed radiation into secondary low energy ionizing radiation.
• These secondary low energy ionizing radiations and nuclear particles, such as alpha particles emitted by the convertor can initiate reaction in the radiation sensitive materials.
• the secondary radiation irrespective of its source can be absorbed by the convertor materials and emit tertiary ionizing radiation which in turn can also initiate a reaction in the radiation sensitive materials.
• the secondary radiations are electrons, use of electroluminescence materials as convertors can amplify the image.
• the image of thin shaped-articles e.g., film can be further amplified by placing it into intimate contact with one or two screens made from convertor materials.
• the screens in their simplest form can be a plain metal foil and/or coated with a radioluminescence, electron luminescence or fluorescence phosphor material, which emits radiation of usually lower energy.
• the X-ray image can be amplified by using phosphor materials, which emit energy higher than 4 eV as screen materials.
• Phosphor materials which emit long wavelength UN light, can be made to emit higher energy radiation by appropriate dopants, quantity of dopants and doping processes.
• An appropriate voltage can also be applied to the screens to produce secondary electrons, which in turn can also initiate reaction in the radiation sensitive materials, thereby also amplifying the image.
• Any material which is an organic, inorganic and/or organometallic compound, which emits radiation of wavelength lower than 300 nm, (energy higher than 4 eN) including those emitted by fluorescence and phosphorescence, upon irradiation with high energy radiation can be used as a convertor for the undercoat, radiation sensitive coat, top coat and the screens. In order to maximize the sensitivity of the film, the selection of a proper convertor is required.
• a convertor which has a high ability to absorb high-energy radiation and emit high intensity radiation of significantly lower energy, but higher than 4 eN, is preferred.
• Electroluminescence phosphors such as hafnium pyrophosphate and those substituted with zirconium, germanium and silicon, which emit UN light or can me made to emit UN light by doping are preferred phosphors. These materials can also be used as convertors if they emit radiation having energy higher than 4 eN, because the secondary electrons can induce cathode luminescence materials to emit UN and X-ray radiation, which in turn can initiate the polymerization of diacetylenes.
• a material which emits radiation having a wavelength shorter than 1 mn can be used as a convertor.
• Preferred are those, which emit UN radiation in the range of 300 to 1 nm. UN radiation is rapidly absorbed by the diacetylene functionality and causes their polymerization.
• a preferred convertor should emit radiation of energy between 300 and 100 nm.
• Materials commonly known as phosphors include those from the II-NII Periodic Table group phosphors (e.g. ZnS, ZnCdS) and a rare earth phosphor (e.g. Gd 2 O2S, Y 2 O 2 S, YTaO or activated YTaO ) and three elemental oxide phosphors (e.g.
• Convertors such as barium lead sulfate, naphthalene-sodium iodide doped with TI, ZrP 2 O (zirconium phosphate), which can emit UN light, can be used.
• Properly doped phosphors such as barium fluorochloride and lanthanum oxybromide, terbium activated rare earth oxysulfide (X 2 O 2 S where X is gadolinium, lanthanum or yttrium), GdOS:Tb(III), LaOS:Tb(III), LaOBr:Tb(III), LaOBr:Tm(III), Ba(FCl) 2 :Eu(II), SrB 4 O 7 :Eu (strontium europium borates), BaS- 2 ⁇ 5 :Pb (barium silicate), (CeBa)MgAl ⁇ O 19 (cerium, barium-magnesium aluminate), strontium pyrophosphate activated with europium, and phosphates of zirconium, germanium, silicon and hafnium can emit short wavelength UV light.
• the preferred phosphor is the one, which emits short wavelength UV light (e.g., 300
• convertors For monitoring neutrons, compounds having a high neutron cross-section are preferred convertors.
• the neutron cross-section for boron decreases as the energy of neutrons increases.
• Naturally occurring boron compounds have about 20% boron-10.
• Amines form a complex with boric acid.
• Boric acid (BA) is nontoxic and inexpensive.
• Shaped-articles containing boron and lithium, especially boron, as a convertor can be used for monitoring thermal neutrons and boron-neutron capture therapy.
• Elements having high neutron cross-section and emitting electrons and gamma rays, e.g., gadolinium can also be used as a convertor for neutrons.
• Scintillation materials emit short light pulses after excitation by the passage of charged particles or by photons of high energy.
• Scintillating material can be organic (solid crystals, plastics, i.e. synthetic polymers, or organic liquids such as toluene, xylene and alkylated benzene, fluorobenzene and p-dioxane), inorganic (crystals or glasses) or gas.
• organic crystals are anthracene (C14H10), trans-stilbene (C14H12), or naphthalene (C10 Hg ).
• two- or three-component scintillators are common, with a solid solvent, doped with aromatic compounds or with wavelength shifters; polysterene and polyvinyltuolene are most commonly used.
• Inorganic crystals include Na(Tl), CsI(Tl), and BaF2; high-Z crystals make good high-energy physics scintillators.
• gaseous or liquid scintillators one uses Xe, Kr, Ar, He, or Ne.
• ionizing particles provoke an excitation of molecular levels, which causes light in the UV region to be emitted.
• Organic Scintillators plastics, liquids
• Plastic Scintillators are non-fluid solutions consisting of fluorescent organic compounds dissolved in a solidified polymer matrix.
• Liquid Scintillators are fluid solutions with similar fluorescent organic compounds.
• Plastic and Liquid Scintillators can be loaded with elements such as Boron, Lithium and Gadolinium for increased thermal neutron sensitivity and Lead or Tin (the latter only in Liquid Scintillators) for increased X-ray and Gamma-ray sensitivity.
• System can be used to monitor the dose distribution of electrons, muons, protons, alpha particles, x-ray/gamma ray, neutrons and atomic nuclei.
• the energy that can be detected include thermal neutrons ( ⁇ 0.5 V) to high energy radiation having energy 50 MeV.
• Low energy neutrons are detected by loading a scintillator with elements that have a high neutron capture cross section. When a neutron is captured, various charged particles are released and detected by the scintillator.
• the most common loading elements are 6 Li, 10 B, and Gd. Scintillators loaded with these elements are listed below.
• the Q value of a reaction is the excess energy that is imparted to the charged particles. Increased detection efficiency is achieved by moderating the incident neutrons to thermal energies and using one of the capture reactions.
• any solid substrate having a smooth surface can be used for coating radiation sensitive shaping formulation and making film
• preferred substrates are flexible and transparent plastic film, and natural (cellulose) and synthetic (e.g., spun bonded polyolefms, e.g., Tyvek R ) papers.
• Plastic films such as polyethylene, polypropylene, polyvinylchloride, polyvinylidene, polyepichlorohydrene, chlorinated polymers and oligomers, polymethylmethacrylate, polyurethanes, nylons, polyesters, polycarbonates, polyvinylacetate, cellophane and esters of cellulose can be used as the transparent substrate.
• Metal foils, such as aluminum can also be used.
• the most preferred substrates are 5 - 300 microns thick films of polyethylene terephthalate. Self- supporting film, plaque and block do not require substrate.
• a large number of pre-polymer systems can be used for making the radiation sensitive shaped-articles.
• polyepoxide, polyurea, polycarbonate, polyester, polysilicones and polyurethane are preferred.
• the oligomeric pre-polymer systems such as diepoxide, diamines, diols and diisocyanates, are available commercially from several suppliers such as Dow, Monsanto, Witco, Union Carbide and several small companies. Proper molecular weight and formulation can be selected so that diacetylenes dissolve in the pre-polymers at higher temperatures and precipitate/crystallize at room temperature. Non-diacetylenic radiation sensitive materials would not require crystallization.
• a crosslinked (thermoset) shaped- article can be obtained. It is also possible to cast shaped-articles by mixing a radiation sensitive material/system with a thermoplastic in molten state and injecting/pouring in to a mold of the shaped-article.
• the binder polymers can be homopolymers, copolymers, graft-copolymers, block copolymers, polymeric alloys and mixtures thereof.
• a large number of monomers and oligomers are used to make polymers.
• They include unsaturated monomers such as olefins, vinyls, acrylates, and methacrylates such as methylmethacrylate, methylacrylate, styrene, acrylic acid, butane diol 1,4- dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, hexanediol-l,6-dirnethacrylate, methylstyrene-alpha- pentaerylthriol triacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, triethylene glycol dimethacrylate, 4-(Vinyloxy) butyl benzoate, bis[4- (vinyloxy)butyl] adipate, bis[4-(vinyloxy)buty ⁇ ] succinate, 4-(Vinyloxy) butyl benzoate, bis[4- (vinyloxy)butyl] adipate,
• the resultant shaped-articles were irradiated with X-ray.
• the shaped-articles developed color.
• the preferred monomers and oligomers are olefins, vinyl and acrylates.
• the most preferred monomers and oligomers are methylmethacrylate and polyethylene glycol dimethacrylate.
• Diacetylene such as 166, 4BCMU, TCME, PCME, PC, and TC were dissolved in molten polymers such as polybutylene, polybutylmethacrylate, polybutylmethacrylate/isobutylmethacrylate, polyethylene, poly(ethylene-co-acrylic acid), poly(ethylmethacrylate), polyethylene/vinylacetate, poly(isobutylmethacrylate), polyvinylbutyral, polyvinylbutyral, polyvinylchloride, polyvinylstearate, poly(ethylene- co-acrylic acid), ⁇ oly(ethylene-co-methacrylic acid), polybutadiene, polyvinylacetate, poly(ethyelene-co-butylacrylate-co-carbon monoxide), poly(o-cresyl glycidyl ether)- formaldehyde, poly(ethyelene-co- 1 -butene), poly(ethy
• Molten mixtures were cooled to room temperature. Depending upon the polymer and diacetylene, opaque, transluscent and transparent shaped objects were obtained. Molten mixtures were casted in to shaped-articles such as thin film, plaque and blocks and exposed to X-ray. Most of the shaped-articles developed color upon irradiation. Other radiation sensitive materials can be used instead of diacetylenes. Most of the melt processible polymers can also be used for radiation sensitive materials other than diacetylenes. Preferred polymers for melt processing are those which provide transparent shaped-articles. The most preferred by polymethylmethacrylate, polystyrene, polyester, poly(ethylene-co-acrylic acid) and polyvinylacetate.
• solvents and plasticizer can also be added in formulation for proper crystallization of diacetylenes or dissolution of radiation sensitive dyes and to adjust the temperature of clarity of the block and plasticization of the binders.
• Use of solvent and plasticizer will depend upon several factors such as nature and concentration of radiation sensitive materials, binders, and additives.
• Preferred solvents are high boiling solvents, plasticizers and liquid oligomers.
• the most preferred solvents are dioctylphthalate, ethylene glycol diacetate and ethyl salicylate.
• binders that can mainly be used to make the dosimeter for measuring dose in three dimensions are water soluble polymers which have the capability of forming gels at room temperature. They include natural and synthetic polymers such as gelatin, agar and polyacrylamide. Inorganic materials normally known as sol-gel materials, can also be used. Gelling could be due to chemical crosslinking as well. In this type of systems, preferably everything is water soluble, as water is one of the major components of the solvent.
• non-aqueous co-solvents such as ethanol can be added.
• ethanol aqueous co-solvent
• gelatin as a binder
• leuco malachite green as indicator
• trichloroethanol as an activator
• wate ⁇ ethanol mixture as a solvent.
• the mixture was made essentially colorless by adding a required amount of ammonia and cooling to room temperature to make the gel.
• the gel developed light green color when irradiated 50 Gy of 100 KeV X-ray.
• the gel does not have to be aqueous.
• a transparent candle gel purchased commercially from The Chemistry Store, Pompano Beach, FL, which is based on U.S. Patent No. 5,879,694. This gel uses mineral oil as a solvent.
• a polymer latex purchased from Liquid Plastic, Limit MFG Corp., Richardson, TX, which forms gel when heated and cooled room temperature and (3) a silicone polymer made by mixing two components.
• Both aqueous and non-aqueous gel systems can be used for determination of the dose distribution in three dimensions. In non-aqueous gels, a solvent is not required, however, a solvent can be used.
• a topcoat of about 0.5 - 2 microns is usually applied to make the coating resistant to abrasion.
• the topcoat can contain a convertor, such as lead iodide and sodium iodide, which is capable of producing radiation of lower energy when irradiated with the high-energy radiation thereby enhancing the image.
• the convertor material can be the same or different depending upon the binder used. As the film does not require wet processing, any scratch resistant polymers can also be used as the topcoat.
• the protective coat can also contain a convertor material, a low molecular weight UV absorbing compound, and other additives, such as an antistatic compound.
• topcoat contains additives, such as a convertor, a scratch resistant protective coat can be applied on the topcoat.
• This topcoat can be polyurethanes, polyepoxy, and polyacrylics, which provide a hard protective coat.
• a container can be considered as a top coat.
• Ionic and nonionic surface-active agents can be used as surfactants.
• Pluronic R Gafac R RS-710, sodium dodecyl sulfate, cetyltrimethyl ammonium chloride, ethoxylated para-octylphenol, 2-ethyl-hexyl alcohol ethoxylate, lecithin, polyethylene glycol and PEG-dodecylether are some examples of surfactants, which can be used to make radiation sensitive shaped-articles.
• Preferred concentration of surfactant in the mixture is 0.01 to 5%, most preferred is 0.1-2%.
• the temperature of cooling the moldable mixture will depend upon several factors such as the nature of radiation sensitive materials, their solubility in binders, nature of binder, other additives such as convertors, surfactants and catalyst.
• the preferred temperature for cooling the moldable mixture is room temperature.
• the blocks can be irradiated alone, in a plastic, glass or other transparent containers, including heat shrinkable plastic containers. Blocks can also be spray coated to prevent migration of chemicals on the surface. If required, the block can be kept in a transparent container.
• the preferred transparent container is glass or plastic.
• the block can be spray coated with a polymer containing a UV absorber.
• the radiation sensitive shaped-articles can be used for monitoring radiation dose.
• the film can be used for verification, imaging, field size coincidence, as a transmission check, measuring portal radiation and beam data acquisition (depth dose, field flatness, beam symmetry and dosimetry), mapping/calibration of brackytherapy and three dimensional dosimetry.
• the shaped-articles can also be used for monitoring UV exposure, e.g., by sunbathers. The UV exposure can be estimated from a reference color chart.
• Radiation sensitive formulations such as diacetylenes 166 and their cocrystallized mixtures, which when exposed to UV light, develop a color and when heated become inactive to radiation can be used for making a high speed printing paper and labels.
• a paper coated with such compositions can be printed using a mask at extremely high speed. Printing can be done with a UV lamp using a negative/mask or using a UV laser. When the paper is heated, e.g., by passing between heated rollers, it will get fixed and become inactive to radiation.
• the printing papers can be prepared by coating them with the radiation sensitive composition using the conventional and those procedures disclosed herein. Desired colors can be obtained by mixing proper radiation sensitive materials in proper proportions.
• the radiation devices can be fixed by processes disclosed in U.S.
• Patent No. 5,420,000 Patent No. 5,420,000.
• Medical supplies are sterilized with gamma ray, X-ray and electrons.
• the radiation dose required for the sterilization varies from a few tens of kilo Gy to a few hundred kilo Gy.
• the shelf life of whole blood and that of a wide variety of foods is extended by irradiating with low dosage (0.01-1 kilo Gy) gamma rays and electrons.
• Many coatings are cured by UV light and UV curable inks are widely used to avoid air pollution.
• the radiation dose for all these applications can be monitored using radiation sensitive formulations and processes disclosed herein.
• the preferred temperature range of irradiation is between -40°C and 60°C The most preferred temperatures are 4°C and room temperature (25°C).
• Irradiation of such a block can be used for mimicking radiation therapy and similar treatments.
• a large number of pre-polymers and polymers, and processes described earlier can be used.
• Any desired shaped block can be obtained by using appropriately shaped mold. For example, for radiation therapy of a hand, a radiation sensitive block in shape of hand can be molded or casted and irradiated from different angles.
• the block can be scanned with an appropriate scanning technique such as MRI and optical.
• Scan data can be processed and used for planning radiation therapy treatment.
• An image produced in the block by the irradiation can be scanned with MRI and optical techniques.
• An optical scanner may incorporate a laser, photodiode detectors, and a rotating platform for the gel or alternatively a lamp, color filter, light diffuser, rotating platform for the block and a digital camera. Data can be acquired for each incremental rotation of the platform. Using the set of optical-density projections obtained, a cross-sectional image of the radiation field is then reconstructed. Dose can be determined from calibration data and optical density measurement.
• the radiation sensitive shaped-articles offer many major advantages over other similar devices. They are simple devices such as just a piece of plastic. They will be an inexpensive. Radiation sources can be imaged in three dimensions. They will be tissue equivalent and hence no corrections will be required. They will be a self- developing and instant device. The images can be fixed for archiving the results. They can be used as a personnel and area dosimeter. They will be highly sensitive. They will be able to monitor very low dose ⁇ 1 mGy. Dose can be determined with an accuracy better than 5% with a spectrophotometer or colorimeter. They can be used over a wide dose range (1 mGy to 100,000 Gy). The color development of the device will be essentially independent of the energy and the dose rate.
• the device is preferably a pre-determined shape depending on the application. If three-dimensional dosimetry is not necessary the radiation sensitive material can be in the form of a film, which is thin and planar, or a coating on a shaped, or planar, substrate.
• the device can be in the shape of a fiber, which is defined herein as having a high aspect ratio of greater than about 20:1, a rod, which is defined herein as having an intermediate aspect ratio of about 5:1 to below 20:1 or a block, which is defined herein as having a low aspect ratio of less than 5:1.
• the aspect ratio is defined as the ratio of length to a diameter of a circle having the same surface area as a cross-section of the device.
• the device can have a regular geometric pattern, defined herein as a regular geometrical shapes formed by the area enclosed by arcs or by multiple intersecting planes such as trigonal pyramidal, rectangular, rectangular pyramidal, etc.
• the device may be in the form of an irregular geometric pattern which have no gross defined shape. Irregular geometric patterns include biological shapes such as hands, feet, etc. or shapes which are specifically formed to have varying thickness to accommodate a sample or to provide calibration areas and the like.
• the plaque and block have major desirable features for monitoring dose in three dimensions.
• The can be a solid self- standing matrix. They can have a highly transparent matrix with low refractive index.
• the image representing dose is in color.
• the image is transparent.
• the image is stable.
• the image has good color intensity within about 1 Gy.
• the image develops almost instantly.
• the image is scannable with simple scanners, e.g., optical scanner.
• the device is energy independent and dose rate independent. There are no post radiation effects.
• the image is linear with dose. All materials are non-toxic.
• the device has a long shelf life and long archival life. There is minimal effect of temperature of irradiation. Multi-exposure can be given and evaluations of cumulative doses can be made.
• the devices have high resolution. The can be easily manufactured at low cost. There is no effect of ambient conditions such as oxygen, light and humidity before and after imaging. The devices are environmentally safe to dispose of.
• the image is fixable and once fixed the image can be stored
• EXAMPLE 1 A pH dye as indicator, a halo compound as activator and use of two reactants to make the binder.
• the system comprises:
• Trichloroethane Indicator Leuco malachite green
• Catalyst A tin compound, (Metacure T-9 of Air Products, Allentown, PA) Procedure: 15g of the poly(propylene glycol) with a MW of about 1000 was mixed with a leuco malachite green solution comprising about 3 grams of dye in trichloroethane. To the mixture were added lOg of poly(isophorone diisocyanate) MW 1550 and 10 drops of the catalyst followed by mixing. The mixture became solid in about ten minutes. When irradiated with 50 Gy of 100 KVP X-ray the mixture turned light green.
• EXAMPLE 2 pH sensitive dyes as indicators, halocarbons as activators and binder from monomer and polymer mixture.
• the system comprises:
• Binder HH772 Acrylic Casting and Embedding Kit (Polysciences, Warrington, PA 18976)
• Indicator Leuco malachite green Activator: Trichloroethane (TCE)
• Many dyes changed or developed colors e.g., acid sensitive dyes such as pentamethoxytriphenylmethanol (PTM) changed from colorless to red, radiochromic dyes such as hexahydroxy ethyl violet changed from colorless to violet, pararoseaniline cyanide changed from colorless to red, triphenyl tetrazolium chloride changed from colorless to red, carbinol (base) dyes such as malachite green base changed from colorless to green and leuco dyes such as leuco crystal violet changed from colorless to violet, when irradiated.
• acid sensitive dyes such as pentamethoxytriphenylmethanol (PTM) changed from colorless to red
• radiochromic dyes such as hexahydroxy ethyl violet changed from colorless to violet
• pararoseaniline cyanide changed from colorless to red
• EXAMPLE 3 Use of liquid diacetylene as an indicator and two reactants to make the binder.
• the system comprises: Binder: Poly(ethylene glycol) MW 400 and 1,6-hexamethylene diisocyanate
• Indicator Methyltricosa-10,12-diynoate (TCME), mp 18-19°C
• Catalyst Triethylamine Procedure: A mixture of 30.5g of poly(ethylene glycol) and 15.5g 1,6-hexamethylene diisocyanate was prepared in a jar. To the mixture was added while stirring 1.5g triethylamine and 4.5g TCME. The mixture was heated slowly at 70°C and then cool to room temperature. The mixture became transparent solid within 30 minutes. The solid became opaque in a refrigerator ( ⁇ 7°C) and in a freezer ( — 20°C). The sample was irradiated with 5 Gy of 100 KVP X-ray on an ice block. The irradiated portion turned blue. Upon bring to RT, the sample became clear and the irradiated portion changed to red.
• EXAMPLE 4 High melting, high molecular weight polymers as binders
• the system comprises:
• Binder Poly(isobutyl methacrylate), MW 260,000
• TCME Methyltricosa-10,12-diynoate
• the system comprises:
• the sample was frozen at -20°C and irradiated at ⁇ 4°C with 5 Gy of 100 KVP X-ray.
• the irradiated portion of the TCME sample turned blue and changed to red when brought to room temperature.
• the sample of 4BCMU remained blue and was slightly opaque but became red and clear at ⁇ 70°C.
• a number of other polymers were also used.
• EXAMPLE 6 Increase in reactivity by cocrystallization
• the system comprises:
• Indicators Tricosa- 10,12-diynoic acid (TC) and pentacosa- 10,12-diynoic acid (PC) Binder: PPG-DM-560 (Polypropylene glycol diacrylate mol.wt. 560)
• the system comprises:
• Methyltricosa-10,12-diynoate TCME
• Methylpentacosa-10,12- diynoate PCME
• Binder PPG-DM-560 (Polypropylene glycol diacrylate mol.wt. 560) Catalyst: 5% Benzoyl peroxide in dioctylphthalate
• Promotor N,N-Dimethyl-p- toluidine Procedure: In a vial 3.8g TCME and 1.9g PCME were dissolved in lOg PPG-DM-560. To the mixture was added 3 drops of promoter and 1.25 ml of catalyst and mixed. The mixture was allowed to cure in the oven at 40°C and cooled to -20°C in a freezer. The sample was irradiated cold with 5 Gy of 100 KVP X-ray. The irradiated portion of the sample turned blue and changed to red when brought to RT.
• EXAMPLE 8 Curing with UV light.
• the system comprises:
• Binder Polypropylene glycol dimethacrylate mol.wt. 560 (PPG-DM-560)
• UV catalyst 10% benzoin methyl ether in dibutyl phthalate Procedure: In a test tube was added ⁇ 2ml of the PPG-DM-560, 1 ml of TCME and 2 drops of the UV catalyst and mixed. The mixture was then exposed to a long wavelength (350 nm) UV lamp at a distance of 25 cm. The sample solidified within a few minutes. [00164] The sample was frozen at -20°C and irradiated with 5 Gy of 100 KVP X-ray. The irradiated portion turned blue and changed to red when brought to room temperature.
• EXAMPLE 9 Polymeric diacetylene as a binder and indicator.
• the system comprises: Diol: 10,12-Dodecadiyene diol
• Binder Polypropylene glycol diacrylate mol.wt. 540 (PPG-DA-540) Catalyst: Benzoyl peroxide
• Plasticizer Dibutyl phthalate Indicator: Methyltricosa-10,12-diynoate (TCME) Procedure: In a test tube was taken lOg of PPG-DM-540, 3.75g of TCME and 0.75g 10%o benzoyl peroxide in dibutyl phthalate. The test tube was annealed at 65°C. The mixture became a highly transparent solid within 20 minutes. The test tube was removed from the oven after 40 minutes.
• TCME Methyltricosa-10,12-diynoate
• the samples became opaque in the refrigerator ( ⁇ 7°C).
• the sample was irradiated cold over an ice block (a part of the test tube was covered with a metal plate to block X-ray) with 5 Gy of 100 KVP X-ray.
• the irradiated portion turned blue and became red when brought to room temperature.
• the system comprises:
• Binder Poly(ethylene-co-acrylic acid-15% acrylic acid) Release coat: Miller-Stephenson; Urethane Conformal Coating
• EXAMPLE 12 Self-supporting thin films.
• the system comprises:
• Binder Poly(ethylene-co-acrylic acid-15% acrylic acid)
• Indicator 4BCMU [5,7-dodecadiyn-l,12-bis(n-butoxycarbonyl methylurethane)] Procedure: 0.1, 0.2, 0.3, 0.4 and 0.5 gram of 4BCMU was mixed with 5g poly(ethylene-co-acrylic acid 15%). The mixture was heated at ⁇ 150°C to melt and mixed with a mechanical stirrer. The molten mixtures were poured between two glass plates pre-coated with a mold release, using spacer of 150 microns and pressed to make a circle of about 5 centimeter diameter. The samples were cooled to RT and films, which were almost transparent, were removed from the glass plates.
• the system comprises:
• Indicator 4BCMU [5,7-dodecadiyn-l,12-bis(n-butoxycarbonyl methylurethane)] Binder: PPG-dimethacrylate MW-560 (PPG-DM-560) Solvent: Ethyl salicylate
• Catalyst Benzoyl peroxide (lg in lOg of dibutyl phthalate) Procedure: A 2g sample of 4BCMU was dissolved in 20g of PPG-DM-560 in ajar. To the solution was added 4g of ethyl salicylate and 0.5g of 10% benzoyl peroxide solution in dibutyl phthalate. The content was mixed and heated at ⁇ 80°C in a heating block. The mixture became a transparent solid in about 30 minutes. After 30 minutes the jar was removed from the heating block and allowed to cool at room temperature. [00175] The sample was irradiated at room temperature with 5 Gy of 100 KVP X-ray using a metal collimator made from washers having 0.7 cm hole.
• the irradiated portion turned blue.
• a same portion of the sample was irradiated again with 5 Gy of 100 KVP X-ray from a different angle using the metal collimator.
• the irradiated portion also tuned blue.
• the sample was heated at 80°C in an oven for 30 minutes.
• the irradiated portions changed from blue-to-red.
• the sample remained transparent for almost 8 hours at room temperature. After a day the jar became opaque.
• the jar was irradiated with 5 Gy of 100 KVP X-ray from third angle using the metal collimator, the irradiated portion turned blue and upon heating at 80°C, the mass became transparent. All three irradiated portions can be seen.
• EXAMPLE 14 A dye in molten polymer Indicator: Leuco malachite green
• Binder Polyethylene-co-polybutylene, Mw 2,500 (PEB-2500) Procedure: 0.2g dye was added in 2g of molten in PEB-2500 and mixed by stirring at ⁇ 120°C in a test tube. The molten mass was allowed to cool. When exposed to 50 Gy of 100 KeV, it developed faint but noticeable green color. [00177] EXAMPLE 15. Heat fixable block The system comprises:
• Indicator 166 [2,4-Hexadiyn-l,6-bis(n-Hexylurethane)] Binder: PPG-dimethacrylate MW-560 Solvent: Ethyl salicylate Catalyst: Benzoyl peroxide (1 g in 1 Og of dibutyl phthalate)
• Promotor N,N-Dimethyl-p- toluidine Procedure: A lOg sample of 166 was dissolved in lOOg of PPG-DM-560 and 30g ethyl salicylate in a beaker. To lOg of the above mixture in a vial was added 1 ml of 10% benzoyl peroxide solution in dibutyl phthalate and 0.25 ml of the promotor. The mixture was stirred and the vial was quenched with liquid nitrogen and allowed to come to room temperature. Another similar vial was placed in a freezer at -20°C and removed after a day from the freezer. A third similar vial was cooled in a refrigerator at ⁇ 7°C. The vials were solid and opaque.
• the samples were irradiated at room temperature with 5 Gy of 100 KVP X- ray. The irradiated portion turned red. The irradiated samples were heated at 70°C in an oven for 30 minutes. The samples became transparent and irradiated portions changed from red-to-purple/blue.
• EXAMPLE 16 Coating of on a substrate
• the system comprises:
• Binder Poly(ethylene-co-acrylic acid-15% acrylic acid)
• Binder Polyethylene-co-polybutylene, Mw 2,500 (PEB-2500)
• Activator Ethyltrichloroacetate
• the system comprises:
• Solvent Ethylene glycol diacetate
• Catalyst Benzoyl peroxide (lg in lOg of dibutyl phthalate)
• Promotor N,N-Dimethyl-p- toluidine
• 1.25g of 4BCMU was dissolved in lOg of PPG-DM-560 and 2g of ED and 0.05g of the promotor were added.
• To the mixture was added 0.5g of the catalyst solution, mixed and allow to set at 40°C. After a day the vial was cooled in a freezer for a day and brought to room temperature. The sample was irradiated at room temperature with 10 Gy of collimated 100 KVP X-ray. The irradiated portion turned blue.
• Binder Liquid Plastic, Limit MFG Corp., Richardson, TX Indicator: TCME
• TCME liquid polymer
• a commercially available antistatic source of 50 micro Curie polonium-210 was placed on a block prepared according to Example 18 for ten minutes. Polonium-210 emits alpha particles of 4.5 MeV. The image of the source was obtained in blue color. When the block was heated it turned red. The results indicate that the block can be used for monitoring alpha particle therapy treatment. When boron- 10 is irradiated with neutrons, it emits alpha particles. Thus this type of dosimeter containing boron- 10 can be used for monitoring neutrons. [00190] Similar results were obtained when the polonium-210 source was placed on a plaque of example 11.
• EXAMPLE 22 Irradiation with therapy radiation
• the system comprises:
• Binder Polypropylene glycol diacrylate mol.wt. 540 (PPG-DA-540) Catalyst: Benzoyl peroxide Promotor: N,N-Dimethyl-p- toluidine Plasticizer: Dibutyl phthalate
• Indicator Methyltricosa-10,12-diynoate (TCME) Procedure: In a one liter jar was taken 300g of PPG-DM-540, 90g of TCME and 2g of 10% benzoyl peroxide in dibutyl phthalate. To the mixture was added 0.25g of promotor, mixed and allowed to solidify at room temperature. The mixture became a highly transparent solid within 20 minutes.
• a sample prepared according to example 18 was scanned using an optical scanned similar to that described by Wolodzko et al. [J.G. Wolodzko, C. Marsden and A. Appleby, Med. Phys. Vol. 26, 2506 (1999)]. Three-dimensional imaging was accomplished by tomographic reconstruction from two-dimensional images acquired using a diffuse fluorescent light source (400-700 nm), a digital charged-couple device camera and SPECT (single photon emission computed tomography) software. [00196] The sample, similar to that shown in Figures 6 and 7, was placed in a rectangular water bath located inside the scanning apparatus.
• FIG. 8 shows a reproduction of a summation of 16 single transverse adjacent slices through the center of the cylindrical sample to improve signal/noise.
• the outer dark ring on these images is the glass wall of the sample container.
• the inner dark spot is the region that was irradiated.
• a diameter across the transverse beam image illustrated in Figure 8 was selected and a relative density profile is shown in Figure 9.
• the density profile and isodose plots demonstrate the sharp fall-off in radiation dose at the edges of the irradiated region. Similar density profile and isodose plots along the beam and 3D dose distribution in the block were obtained.
• the sample can be placed in a liquid such as glycerol and other higher refractive index fluid and scanned.
• a block can be scanned before and after irradiation and subtracting the before radiation scan that from the radiated one.

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